A conventional mask pattern creation method is described with reference to FIG. 8. In the conventional system, mask pattern data created by a mask pattern data creation system 801 is converted to a stream data format, such as GDS (ECMA-96), and is output on a recording medium such as a magnetic tape as stream data 605. Created mask pattern data is used in subsequent steps.
The mask pattern data creation system 801 has a display unit 606 such as a CRT display and a keyboard 607 for I/O processing (user interface).
FIGS. 10 and 11 schematically show the hierarchical structure of mask pattern data. An earlier patent disclosure dealing with the block layout of a hierarchical data structure having a block, sub-blocks of the block, and basic cells which are the lowest-level blocks, etc. is found, for example, in Japanese Patent Kokai Publication JP-A-61-45364.
If there is a limit that the layout angle of layout cell data 1002 which is placed in a lower hierarchical level in the stream data format must be in 90-degree units when creating hierarchically-structured mask pattern data 1001 as shown in FIGS. 10 and 11, a limit that a mask pattern data creation function 802 of the mask pattern creation system 801 must always create layout cell data 1002 in 90-degree units is imposed in order to avoid conflict with the limitation in the stream data format.
However, this method cannot be used to create layout cell data with an arbitrary layout angle other than 90 degrees such as 15 degrees, 30 degrees, and so forth.
On the other hand, Japanese Patent Kokai Publication JP-A-7-146945 discloses a data processing system which expands a continuous pattern in any rotational angle on a word processor or a DTP (Desk Top Publishing) system. FIG. 9 shows the configuration of a system in which the function disclosed by Japanese Patent Kokai Publication JP-A-7-146945 is implemented in the conventional mask pattern data creation function 802 shown in FIG. 8. Although the data processing system disclosed by the above patent publication is not a mask pattern creation system, the following describes a system in which the above-described data processing system with the function of expanding a continuous pattern of any rotational angle is applied to mask pattern data creation. The configuration of this system was invented also by the inventor of the present invention.
As shown in FIG. 9, the mask pattern data creation function 802 has super cell creation means 903 and expansion means (flattering means ) 904. The super cell creation means has a rotational angle storage module 902 which stores into memory angle data .theta. (see 1301 in FIG. 13) entered from a keyboard 607 (see FIG. 8) via a control module 901, and the super cell creation means 903 creates super cells having an arbitrary angle of .theta. stored into memory from layout cell data (1002 in FIGS. 10 and 11). The expansion means (flattening means) 904 expands super cells into graphic data having no hierarchical structure (1201 in FIGS. 12 and 13) onto mask pattern data. This function may create layout cell data with an arbitrary pseudo-angle of .theta. in a hierarchical level lower than that of mask pattern data (1001 in FIGS. 12 and 13). Actually, the layout cell data, which is expanded graphic data 1202 (see FIGS. 12 and 13), is in mask pattern data 1001.